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What is an element?
An element is a pure substance composed on one or more of the SAME type of atoms
What is a solution?
A solution is a homogenous mixture where one substance (solute) dissolves into the solvent
Give an example of a chemical change.
What are ways to tell a chemical change has occurred?
Fireworks
Photosynthesis
Color change, temp change, precipitant, bubbles, odor...
What is a base?
A base is a substance whose pH is 8-14. The substance is composed of OH- ions
What is Cohesion?
Cohesion is the attraction of polar water molecules to other polar water molecules (hydrogen bonding between Hydrogen of one compound and Oxygen of the other)
What is a compound?
A compound is a pure substance composed of two or more DIFFERENT atoms
Where on the periodic table are nonmetals?
What are some characteristics of nonmetals?
Left side
Brittle, gas at room temperature, dull, doesn't conduct heat or electricity
What is the coefficient?
The large number in front of the chemical formula that says how many of the MOLECULES there are
What are characteristics of an acid? Of a base?
An acid is sour, can corrode the skin or metal, has a low pH, turns blue litmus red
A base is bitter, slippery to touch, can burn the skin, has a high pH, turns red litmus blue
What does a polar molecule mean?
Polar means half of the molecule has a positive charge while the other half has a negative charge
List the two pure substances
Elements
Compounds
Where on the periodic table are metals?
What are some characteristics of metals?
Right side
Shiny, malleable, ductile, high melting point, conducts electricity and heat
What is a subscript?
The subscript is the small number to the right of an element that says how many of that specific element there are.
What is the pH of water?
7, neutral
What is adhesion?
Adhesion is the attraction between water molecules and other polar substances (like the wall of the xylem in plants)
What is a homogenous mixture? Give an example
A mixture where the substances are evenly mixed together and are indistinguishable
(coffee)
Where on the periodic table are metalloids?
What are the characteristics?
zigzag line
Semiconductors, "sometimes" shiny, "sometimes" conduct electricity
Explain Conservation of mass
Conservation of mass explains that the total mass of the reactants has to be equal to the total mass of the products. The total number of elements on the reactant side has to equal the total number of elements on the product side.
What are the four properties of water?
Adhesion
Surface tension
Cohesion
Capillary action
What is surface tension?
Surface tension is the ability of water to resist an external force due to the cohesion between water molecules
What is a heterogenous mixture? Give an example
A mixture where the substances are not evenly mixed and usually separate into layers
(salad)
What is the difference between chemical and physical changes?
Physical changes only affect the appearance
Chemical changes change the chemical composition and result in the formation of a product
What is an Acid?
An acid is a substance with a pH value of 0-6. The compound is composed of H+ ions
Explain how capillary action works in plants
Capillary action is the upwards movement of water through the xylem due to cohesion and adhesion
What are the bonds between different water molecules called?
Hydrogen bonds